A vacuum circuit breaker comprising a vacuum interrupter (12) coupled between upper (18) and lower (20) terminals and being operable to make or break an electrical connection between the upper and lower terminals. The circuit breaker has a body 22 formed from electrically insulating material, the vacuum interrupter being located in an internal chamber of the body. The circuit breaker body is arranged to provide an isosceles triangle between the upper (C) and lower (A) terminal connection interfaces. This allows the same design of both upper and lower external connectors 80, 82. A pulling rod (16) coupled to the vacuum interrupter comprises a core (70) of heat-resistant plastic co-moulded with a shell (72) formed from impact resistant plastic.